1. Field of the Invention
This invention relates to a biaryl-type compound, a circular dichroism (CD) color fixing agent for introducing a CD chromophore into a chiral compound and a method for determination of absolute configuration of a chiral compound.
2. Description of Related Art
In compounds having a single functional group such as alcohols, thiols, amines and the like is included a compound having an optical activity referred to as a chiral compound. There are known various methods in order to determine an absolute configuration of such a chiral compound.
Among them, a modified Mosher method using NMR is used most practically and frequently at the present time.
And also, a method using CD is known in the determination of the absolute configuration. As to such a method for the determination of the absolute configuration, there are several reports. For example, Harada et al. of Tohoku University of Japan reports that by condensing a chiral alcohol with di(l-naphthyl) acetic acid as a CD auxiliary group is observed a good correlation between the absolute configuration and sign of exciton chirality (40th natural organic compounds symposia).
Furthermore, Adam W. et al. reports that in case of a chiral benzyl alcohol, by newly introducing a benzoyl group is observed a good correlation between sign of Cotton effect indicated by the obtained benzoate body and the absolute configuration [Journal of Organic Chemistry, 65, pp186-190 (2000)].
However, the modified Mosher method becomes complicated in the operation of determining the absolute configuration and requires at least a few milligram of a sample.
The method of Harada et al. is insufficient in the yield of the derivative and further requires the calculation of a stable conformation through a molecular force-field calculation, so that it has a problem that multistage operations are required in the determination of the absolute configuration.
Furthermore, the method of Adam et al. requires the calculation of the stable conformation likewise the above method, and has a problem that an application range of the chiral compound is restricted.
Since the CD exciton chirality method is based on the interaction of two chromophoric excitons, an application to a compound having two or more functional groups such as diol or the like is restricted.
An object of the invention is to provide a new biaryl-type compound.
Another object of the invention is to provide a new CD color fixing agent by introducing a CD chromophore into a chiral compound.
The other object of the invention is to provide a method for efficiently determining an absolute configuration of a chiral compound.
According to a first aspect of the invention, there is the provision of an achiral biaryl-type compound in which the biaryl-type compound is at least one compound selected from the group consisting of a biphenyl dicarboxylic acid derivative represented by the following general formula (I): 
(wherein R is H, Mexe2x80x94, Etxe2x80x94, i-Prxe2x80x94, n-Buxe2x80x94, i-Buxe2x80x94 or t-Buxe2x80x94 and X is H, Mexe2x80x94, Me2Nxe2x80x94, MeOxe2x80x94, NO2xe2x80x94, NH2xe2x80x94, CNxe2x80x94, Cl or Br, and Y is OHxe2x80x94, CNxe2x80x94, 
provided that X is Me2Nxe2x80x94 or CNxe2x80x94 when Rxe2x95x90H and Yxe2x95x90OH, X is Mexe2x80x94, Me2Nxe2x80x94, NO2xe2x80x94, NH2xe2x80x94 or CNxe2x80x94 when Rxe2x95x90Me and Yxe2x95x90OH, and X is Mexe2x80x94, Me2Nxe2x80x94, MeOxe2x80x94, NO2xe2x80x94, NH2xe2x80x94 or CNxe2x80x94 when Rxe2x95x90Et and Yxe2x95x90OH, and R is t-Buxe2x80x94 when Xxe2x95x90H and Yxe2x95x90OH), 2,2xe2x80x2-binaphthyl dicarboxylic acid derivative represented by the following general formula (II): 
(wherein R is H, Mexe2x80x94, Etxe2x80x94, i-Prxe2x80x94, n-Buxe2x80x94, i-Buxe2x80x94 or t-Buxe2x80x94 and Y is OHxe2x80x94, CNxe2x80x94, 
provided that R is i-Prxe2x80x94, n-Buxe2x80x94, i-Buxe2x80x94 or t-Buxe2x80x94 when Yxe2x95x90OH), 2,2xe2x80x2-biquinoline dicarboxylic acid and derivatives thereof represented by the following general formula (III): 
(wherein R is H, Mexe2x80x94, Etxe2x80x94, i-Prxe2x80x94, n-Buxe2x80x94, i-Buxe2x80x94 or t-Buxe2x80x94 and Y is OHxe2x80x94, CNxe2x80x94, 
and may contain a compound formed by cyclizing xe2x80x94CO2R with xe2x80x94COY to form 
7,7xe2x80x2-biquinoline dicarboxylic acid and derivatives thereof represented by the following general formula (IV): 
(wherein R is H, Mexe2x80x94, Etxe2x80x94, i-Prxe2x80x94, n-Buxe2x80x94, i-Buxe2x80x94 or t-Buxe2x80x94 and Y is OHxe2x80x94, CNxe2x80x94, 
and may contain a compound formed by cyclizing xe2x80x94CO2R with xe2x80x94COY to form 
2,2xe2x80x2-bianthracene dicarboxylic acid and derivatives thereof represented by the following general formula (V): 
(wherein R is H, Mexe2x80x94, Etxe2x80x94, i-Prxe2x80x94, n-Buxe2x80x94, i-Buxe2x80x94 or t-Buxe2x80x94 and Y is OHxe2x80x94, CNxe2x80x94, 
and may contain a compound formed by cyclizing xe2x80x94CO2R with xe2x80x94COY to form 
2,2xe2x80x2-bibenzo(g)quinoline dicarboxylic acid and derivatives thereof represented by the following general formula (VI): 
(wherein R is H, Mexe2x80x94, Etxe2x80x94, i-Prxe2x80x94, n-Buxe2x80x94, i-Buxe2x80x94 or t-Buxe2x80x94 and Y is OHxe2x80x94, CNxe2x80x94, 
and may contain a compound formed by cyclizing xe2x80x94CO2R with xe2x80x94COY to form 
and 3,3xe2x80x2-biacridine dicarboxylic acid and derivatives thereof represented by the following general formula (VII): 
(wherein R is H, Mexe2x80x94, Etxe2x80x94, i-Prxe2x80x94, n-Buxe2x80x94, i-Buxe2x80x94 or t-Buxe2x80x94 and Y is OH, CN, 
and may contain a compound formed by cyclizing xe2x80x94CO2R with xe2x80x94COY to form 
According to a second aspect of the invention, there is the provision of a circular dichroism (CD) color fixing agent for introducing an achiral CD chromophore into a chiral compound, in which the chiral compound is selected from the group consisting of alcohols, thiols and amines, and the CD color fixing agent comprises at least one achiral biaryl-type compound selected from the group consisting of 2,2xe2x80x2-binaphthyl dicarboxylic acid, 2,2xe2x80x2-biquinoline dicarboxylic acid, 7,7xe2x80x2-biquinoline dicarboxylic acid, 2,2xe2x80x2-bianthracene dicarboxylic acid, 2,2xe2x80x2-bibenzo(g)quinoline dicarboxylic acid, 3,3xe2x80x2-biacridine dicarboxylic acid and derivatives thereof and a biphenyl dicarboxylic acid derivative other than biphenyl dicarboxylic acid anhydride.
According to a third aspect of the invention, there is the provision of a method for determining an absolute configuration of a chiral compound, which comprises steps of:
(a) selecting a chiral compound from the group consisting of alcohols, thiols and amines;
(b) introducing an achiral CD chromophore into the chiral compound; and
(c) determining an absolute configuration of the chiral compound from relative bulkiness of a substituent on xcex1-carbon, preferential order in a sequence rule (CIP method) and sign of exciton chirality.
The inventors have reexamined the conventional methods of forming derivatives of chiral compounds and made various improvements thereof in order to efficiently conduct a determination of an absolute configuration of the chiral compound.
As a result, the inventors have found out that a derivative of a chiral compound can be simply formed in a higher yield by introducing an achiral biaryl-type chromophore into a given chiral compound.
Moreover, the inventors have discovered that the absolute configuration of the chiral compound can be determined very simply and efficiently based on a correlation between CD spectrum of such a derivative of the chiral compound and absolute configuration of the chiral compound, and as a result, the invention has been accomplished.
Recently, the inventors developed a CD derivative-forming reagent (biphenyldicarboxylic acid anhydride) applicable to a mono-alcohol, and reported its usefulness in the determination of an absolute configuration (the collection of the 42nd natural organic compound debate lecture summaries, page 571, October, 2000, Okinawa, Japan).
Now, the inventors develop a new reagent capable of more simply forming a derivative from a given chiral compound in a higher yield, and first elucidate a correlation among an absolute configuration of a chiral compound, a relative bulkiness of a substituent on xcex1-carbon, preferential order in a sequence rule, and CD spectrum of a derivative.
The given achiral biaryl-type compounds are novel substances and first discovered in the invention.
And also, the given achiral biaryl-type compound according to the invention can constitute a CD color fixing reagent very useful for the derivative formation of the chiral compound and the determination of absolute configuration thereof.
In the method for the determination of absolute configuration according to the invention, an achiral chromophore is introduced into the given chiral compound. Such an achiral chromophore induces CD in the chiral compound.
In the invention, the achiral chromophore is a material in which a chirality of the chiral compound can be effectively propagated to efficiently determine the absolute configuration of the chiral compound.
The achiral biaryl-type compound, especially CD color fixing agent according to the invention is made possible to simply form a derivative of the chiral compound as a substrate in a high yield to conduct a very efficient determination of absolute configuration.
Moreover, the method for the determination of absolute configuration according to the invention can directly determine the absolute configuration of the chiral compound from a correlation among relative bulkiness of a substituent on xcex1-carbon, preferential order in a sequence rule and sign of exciton chirality without requiring molecular force-field calculation as in the conventional method.